The overall goal of the study is to test the specificity of the antiproteinuric effects of acetazolamide. Studies are performed in 4 consecutive one month periods (l)acetazolamide 250mg bid, (2)acetazolamide discontinued, (3)furosemide at equivalent doses to produce weight losses equivalent to period 1, (4)furosemide discontinued. BP, weight, serum chemistries and 24 hr urines are performed at the beginning, middle, and end of each period.